Is Richard Armitage's secret cameo in Avengers 2... or the Spooks movie?

But aside from finding out which Hobbit cast members Armitage would take with him into a real-life storm, this interview was also notable for an intriguing titbit towards the end.

"I'm doing another movie after I've finished on stage," Armitage told us. "But I can't tell you what it is. But you'll know!"

Intriguing, no? The fact that he's so cagey about details suggests that this is a role with some form of NDA attached, which immediately makes us think blockbuster. So we at Digital Spy have put our deerstalkers on for a spot of what we'll call deductive speculation.

Given that Armitage appeared in 2011's Captain America: The First Avenger as Nazi spy and assassin Heinz Kruger, our first thought was that he might crop up in The Avengers: Age of Ultron.

Yes, Kruger is dead, but when has that ever stopped anyone in the Marvel universe? Rumor has it that Ultron features a 1940s-set flashback sequence, so Kruger could certainly crop up.

Or is Armitage talking about the long-awaited Spooks movie? Once again, his character is a dead man - Lucas North committed suicide in series nine of the BBC drama - but that certainly doesn't rule him out for flashbacks or dream sequences.

The problem with both these ideas is that Armitage is still on stage in The Crucible until September 13, while both Avengers: Age of Ultron and Spooks have already wrapped and are in post-production.

Armitage as Lucas North in Spooks

In either case, Armitage could shoot his cameo during pickups, but it's also possible we're way off the mark with both guesses. Some have been speculating that he'll show up in JJ Abrams's Star Wars: Episode VII, for no particular reason other than that it's being filmed in London and why not?

So what do you think Armitage's secret cameo will be? Share your thoughts in the comments!